A number of vehicle sin use today have road wheels with hub assemblies each constructed of a hub and spindle provided with a pair of antifriction bearings of the ball type. In many of these ball bearing hub assemblies, the hub is mounted to a frame or axle and is stationary, while the spindle is attached to the road wheel and rotates within the hub. In many of the light duty, compact, and subcompact automobiles manufactured today which are provided with front wheel drives, the rear wheels are provided with hub assemblies having ball antifriction bearings not provided with removable races, but instead constructed with a caged set of balls riding in permanent races machined directly into the hub and spindle. Additionally, many rental trailers are provided with this type of ball bearing hub. In this type of hub assembly, known as a unitized hub assembly, the entire hub and spindle, after being machined, is hardened to a hardness on the order of about Rockwell 72 in order to harden the ball races and extend their life. Additionally, these type hub assemblies are permanently assembled and are not provided with any means to be readily disassembled for servicing. Under normal operating conditions, these hub assemblies have a lifespan of about 100,000 miles, after which the grease installed at the manufacturing facility degrades or otherwise loses its antifriction properties or is lost due to a failed seal, the balls of the bearing and their permanent races wear at an accelerating rate, and soon reach a point where they are unserviceable. At this point, the entire hub assembly must be replaced, and since the bearing races cannot be refurbished, the worn hub assembly must be discarded. In one well-known rental trailer commonly in use today, this hub assembly costs about $285, not including labor costs, meaning that if it becomes necessary to replace more than a few of these hubs a year, thousands of dollars in hub maintenance costs a year may be accrued.
In accordance with the foregoing, it is an object of this invention to provide a method for converting permanently assembled and lubricated ball bearing hub assemblies to hub assemblies that may be readily disassembled for servicing.
It is a further object of this invention to convert such ball bearing hubs to tapered bearing hubs in order to extend service life of the hub assembly.